Time delay device



1959 A. VAN RYAN ET AL 2,907,562

TIME DELAY DEVICE Original Filed Sept. 8. 1953 JILL, n l. T] W.WQURT::iTE

INVENTOR. Amnorw VAN RYAN KAzuoHeNRY DATE ATTORNEY United States Patent TIMEDELAY DEVICE Anthony Van Ryan and Kazuo Henry Date, South Milwaukee, Wis., assignors to McGraw-Edison Company, a corporation of Delaware Original application September 8, 1953, Serial No. 379,046, now Patent No. 2,804,521, dated August 27, 1957. Divided and this application October 25, 1954, Serial No. 464,499

1 Claim. (Cl. 2671) This invention relates to a time delay device for a circuit interrupter.

This application is a division of our copending application Serial No. 379,046, filed September 8, 1953, now Patent No. 2,804,521, granted August 27, 1957, for Circuit Interrupter, assigned to the same assignee as the present application.

In circuit interrupters, time delay devices are employed to secure delay in the operation of the circuit interrupter under various conditions. Among others is the two time current type of circuit interrupter in which the circuit interrupter responds to the overload either substantially instantly or after a delay period as described in greater details in our above noted copending application.

Objects of this invention are to provide a time delay device which may be easily applied to or used with a circuit interrupter to secure the desired delay in the operation of the circuit interrupter.

A further and specific object of this invention is to provide a time delay device which has an inverse relation to the magnitude of the overload and which is so constructed that if the overload increases the inverse relation is increased by an automatic adjustment of the time delay device.

An embodiment of the invention is shown in the accompanying drawings in which the single figure is a sectional view through the time delay device.

Referring to the drawings it will be seen that the time delay device indicated generally by the reference character 1 comprises a body portion which is provided with a cylinder 2 within which a piston 3 is slidably mounted. The piston is spring urged upwardly by means of a spring 4. It is adapted to be pressed downwardly against the action of the spring by means of the piston rod 5.

The time delay device is adapted to be filled with oil or other suitably liquid and when the piston 3 is pressed downwardly the fluid beneath the piston passes through an aperture 6 to a needle valve 7 and flows past the needlevalve to the space above the piston by way of the aperture 8. The needle valve 7 is spring urged downwardly by means of the spring 9 and coacts with an apertured plate 10 to normally restrict the aperture through the plate.

The plate 10 is in reality a valve and drops downwardly on the return stroke of the piston to allow free passage of the oil in a reverse direction.

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It will be seen from the construction described hereinabove that as the pressure on the lower end of the needle valve 7 increases the spring 9 will be compressed more and more. This allows a larger and larger opening to occur at the needle valve and consequently allows a greater and greater flow of oil past the needle valve and thus produces less and less delay by the time delay device out of proportion and beyond that produced normally by increasing overloads. In other words, the inverse relation is automatically increased.

The time delay device may be mounted upon a suitable support 11 in any desired manner and is adapted to coact with a suitable portion of a circuit interrupter so that the rate at which the piston rod 5 is pressed downwardly determines the time delay of the circuit interrupter. This last described feature'is set forth in greater detail in our copending application hereinabove noted of which this application is a division.

It will be seen that this invention provides a novel form of time delay device which is so made that its time delay period is inversely as the load but in which this inverse relation is automatically increased as the load increases.

Although this invention hasbeen described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

A time delay device for a circuit interrupter comprising a body portion having a cylinder formed therein adapted to contain fluid, a piston in said cylinder, means located externally of said body portion for transmitting a force to said piston, said body portion having an escape orifice communicating with said cylinder, means controlling said orifice and including a needle valve for gradually increasing the effective area of said orifice as the pressure in said cylinder increases to thereby provide an automatic increase in the inverse relation of the load imposed on said piston and the period of time delay, a spring urging said piston towards its initial position, and a valve for permitting fluid to flow into said cylinder on return stroke of said piston, said last mentioned valve including a movable disc-like member constituting the seat for the needle valve, said body portion having a stationary seat portion normally spaced from said movable disc-like member, said movable disc-like member coacting with said seat portion and movable into engagement with said seat portion by the pressure within said cylinder as the pressure in the cylinder increases.

References Cited in the file of this patent UNITED STATES PATENTS 1,695,933 Shultz Dec. 18, 1928 1,759,879 Ackerman et al. May 27, 1930 1,992,232 Nalle Feb. 26, 1935 2,033,664 Worner Mar. 10, 1936 2,730,354 Burris Jan. 10, 1956 

